Means for turning control shafts to preselected angular positions



1943 LE ROY J. LEHSHMAN 2,325,864

MEANS FOR TURNING CONTROL SHAFTS TO PRE-SELEGTED ANGULAR POSITIONS FiledDec. 15, 957 4 Sheets-Sheet 1 I AM Aug. 3', 1943.

MEANS FOR TURNING CONTROL SHAFTS TO PRE-SELECTED ANGULAR POSITIONS LEROY J. L'EESHMAN Filed Dec. 15, 1937 4 Sheets-Sheet 2 IN VENTORI LE ROYJ. LEISHM AN 2,325,864

MEANS FOR TURNING CONTROL SHAFTS TO PRE-SELECTED ANGULAR POSITIONS FiledDec. 15, 1937 4 Sheets-Sheet 5 Tic]- 11 AINVENTORI Patented Aug. 3, 1943DIEANS FOE TURNING CONTROL SHAFTS TO PRESELECTED ANGULAR POSITIONS LeRoy J. Leishman, Los Angeles, Calif.

Application December 15, 1937, Serial No. 179,910 20 Claims. (oi. 74'1o) This invention relates to automatic shaftpositioning means, and moreparticularly to mechanisms suitable for turning the controls of radioapparatus to predetermined angular positions. Most instruments forvarying the imped- I ance of the circuits of a radio set are equippedwith rotatable control shafts, and gang condensers, which are mostcommonly used for this purpose, ordinarily have rotors that need to beturned through an angle of 180 degrees to cover the capacitive range.Various types of automatic tuners have been devised to rotate and stop.these shafts at the positions required to tune in pre-selectedstations; and those that have been manually operated, or controlled bylevers, have usually been equipped with a plurality of selectivelyoperable means each adapted to rotate thecontrol shaft to a differentpredetermined angular position. Heretofore, however, the manuallyoperable means, or levers, have never been capable of directly rotatingthe shaft through an angle of 180 degreesineitherdirection. Ithasthereforebeen necessary to confine the use of the levers to stations ina given frequency range, as in the tuner of Bird, Patent No. 1,925,651;or to sacrifice a few degrees of rotation, as has been done with theheart-shaped cam tuners of the past; or to increase the rotation bymeans of gears or pulleys, as in the device of Schaefer, Patent No,1,906,106. or my own device, Patent No. 2,084,851. shaped cam tunershave had the additional defect of. requiring too much pressure tooperate the levers, due to the extremely short moment arms involved andthe inherent inefl'iciency of cams as a means of transmitting motionwhen operated by the follower. The objects of the present invention areto increase the angular movement of the rotatable member in tuners ofthe type described; to provide a mechanical tuner in whichthe levers orpush buttons will rotate a tuning condenser through an angle of 180degrees in either direction without the use of gears; to supply anoperating means that moves in a straight line; to achieve theaboveobjectives through rotatable members that have long moment arms; tofurnish a dial transmission that operates very easily; and to make itpossible to assemble much of the mechanism directly on'the condensershaft in order to simplify the construction, attain a high degreeescutcheon through which the lever protrudes on the front of the set.

Heart- Fig. 3 shows the mechanism of Fig. 2 in a clockwise transitory,and in the tuned-in, position.

Fig. 4 shows the same mechanism about to turn the rotatable membercounterclockwise, and as it appears in a counterclockwise transitoryposition:

Fig. 5 is a plan view of the lever shown in the foregoing figures,

Fig. 6 shows a modification in which the rotatable member may be turned180 degrees in either direction through the use of a lost-motion link onthe lever-assembly.

Fig. 7 shows a modification using a lost-motion link on the controlshaft, and the rotatable mem-- her is shown in the furthestcounterclockwise position-i. e., in the position from which it can onlymove in a clockwise direction.

Fig. 8 shows the mechanism of Fig. 'l in a transitory position as therotatable member is being turned clockwise, and, in dotted lines, the

tuned-in position.

Fig. 9 shows the mechanism of the last two figures with the rotatablepositionable member in the furthest clockwise position as it is about tobe turned counterclockwise, and the dotted lines indicate a transitoryposition in the counterclockwise rotation.

Fig. 10 is a plan View of the lever used in the device of Figs. 7, 8 and9. s

Fig. 11 is a front elevation of an automatic tuner and scale, showing aplurality of operating levers and positioningmeans of the typeillustrated in Figs. 7, 8 and 9, with the latter mounted on thecondenser'shaft.

Fig. 12 is a side elevation of the right end of the tuner depicted inFig. 11, showing features of the dial transmission.

Fig. 13 is aside elevation of the left end of the device of Fig. 11,showing details of the drive to the horizontal dial.

Fig. 14 shows a modification 'in which the oper- Fig. 16 is a frontelevation of a push-button operated mechanical tuner in which thepositionable means are mounted on the condenser shaft.

Fig. 17 shows a modification of the mechanism of Figs. 14 and 15 inwhich friction is somewhat lessened by means of rollers that are alsoapplicable to the forms of the invention illustrated in the otherpreceding figures.

It has heretofore been impossible in lever-operated automatic tuners touse identical positionable members for all the levers and yet secure anangular rotation of degrees in either direction upon operation of one ofthe levers.

Thi difficulty arises from the fact that when a positionable member isin an extreme angular position 180 degrees from the tuned-in position,the

extreme position is the same regardless of the direction in which themember turned in reaching that extremity of its motion. Whether itshould be turned to the right or left, the operating means thereforefinds the positionable member in identically the same position, whichthus becomes a dead end position. When heartshaped cams are used as thepositionable mem-v bers, each cam can therefore be permitted to turn tothe right or left only to such a position as will enable the roller toengage either the right or left edge. In addition to sacrificing thesefew degrees of rotation that the condenser ordinarily requires, thecontour of heart-shaped cams is such that they are very hard to turn, adefect that is complicated by extremely short moment .arms with respectto the force applied bythe operating lever.

Short moment arms are unavoidable if the operating means has only asingle roller or contact projection for urging the positionable memberin either direction.

Figs. 1 to illustrate an arrangement in which the diificulties ofunsatisfactory contours and short moment arms are both eliminated by the.provision of multiple contact projections that move in differentplanes. Projection D on the operating lever L, pivoted on rod Q, movesin the same plane as arm B of the positionable member A mounted on shaftS, and its function is to move the positionable member through part ofits clockwise movement. Projection E on the operating means L moves inthe same plane as arm C on the positionable member, and engages arm 0during the first part of the counterclockwise movement of thepositionable member. Positioning member F, riveted, or otherwiseattached, to the operating means L, moves in the same plane as arms Gand K of the positionable member, and engages either arm G for the finalpart of the counterclockwise rotation of member Y A, or arm K forturning member A through the last part of its clockwise rotation.

In Fig. 2, the positionable member is shown in its extremecounterclockwise position, and the downward movement of operating meansL must therefore turn it in a clockwise direction. Positionable memberA3, Fig. 1, is shown in this same position, as Fig. 2 is substantially asectional view taken on line 2i of Fig. 1, with escutcheon I added. Whenbutton P, Fig. 2, is pressed down, projection D engages arm B androtates the positionable member in a clockwise direction until it almostreaches the position shown in full lines in Fig. g, The inner edges ofprojections E and D are shaped so that they will pass over the centerportion of member A and beyond shaft S. Posi tioning means F now engagesarm K of member A and rotates the member until further movement isstopped by the collision of arm G with member F. The lever andpositionable member are now in the tuned-in position indicated in dottedlines in Fig. 3, and the rotatable member has been rotated substantially1'70 degrees.

Fig. 4 shows positionable member A in the extreme position that it mayoccupy after the clockwise rotation of shaft S on which the member ismounted. It will be observed that this an ular position of thepositionable member is about degrees from the extreme counterclockwiseposition pictured in Fig. 2, and that the two extreme positions areprevented from coinciding by projection E. Each extreme position is thusabout 10 degrees from a mean position. In this extreme clockwiseposition of member A, the downward movement of lever L causes projectionE to engage arm 0 and rotate the member to the position indicated indotted lines. The continued downward movement of operating means Lcauses positioning member F to engage arm G of the positionable memberand rotate it until further movement is stopped by the engagement ofpositioning member F with arm K on the opposite side of the shaft orfulcrum from arm G. This is the tuned-in .position shown in dotted linesin Fig. 3, and represents a rotation of degrees in a counterclockwisedirection from the initial position pictured in Fig. 4.

Fig. 5 is a plan view of lever L, showing projection D, member F, andthe end H, which is formed so that the outer portion T is parallel tothe plane of the main body of the lever. The turned end T and the end ofthe lever proper have holes V and W respectively for pivoting the leveron rod Q.

In Fig. 1, a plurality of positioning means Ll to H are shown pivoted onrod Q, attached to the two parallel end-plates XI and X2. A plurality o1positionable members Al to A4, cooperating respectively with positioningmeans Ll to L4, are mounted on shaft S, journaled in the two end-plates,which are attached to the chassis Y. Positionable member A3 is picturedin the position of member A in Fig. 2, and member Al is shown turned tothe tuned-in position by the action of lever L4, pressed down by theoperator's finger, indicated in dotted lines.

A bumper ll! of resilient material extends from one end-plate to theother to limit the upward motion of the operating means or levers. Inthe form shown, this is a tube, preferably of rubber, surrounding a rodQ3. Each positioning means is held against this bumper by a spring J,Fig. 2, attached to support Q4. This support and the springs for leversLl, L2 and L3 have been omitted from Fig; 1 for the sake of clearness.

Any desired number of levers and cooperating positionable members may beused, but the preference of most engineers seems to range. from six tofifteen.

A pulley Zl is mounted on shaft S, operatively connected by cords 8 and9 to pulley Z2, on which the other ends of these cords are reeled,Pulley Z2 is keyed to shaft Q2, to which the operating knob, not shown,is attached. Coupling 5 connects shaft S to shaft 8 on which the rotorplates 1 of the condenser are mounted.

The levers ordinarily protrude through slots in an escutcheon on thefront of the set, as indicated in Fig. 2, where lever L is shown passingThe index tab 0 is first removed. Lever L is then pressed all the waydown, thus rotating the positionable member to the tuned-in positionandbringing the set-screw R directly behind hole U in the escutcheon. Whilethe lever is held down,

-th e set-screw is loosened by means of a screwdriver inserted throughwindowN and hole U.

- i2 to the position indicated in dotted lines.

The desired station is then tuned-in by the manual knob that rotatesshaft Q2. After this has been done very carefully, the set-screw isagain tightened, the lever allowed to flip back to its rest positionagainst bumper l0, and an index tab, bearing the station call-letters,is placed in the proper recess between the holder M and the escutcheon.Any subsequent complete downward movement of the operating means, orlever, will return the positionable member to thissame angular positionand thus tune in the same station.

Although the mechanism just explained, like those using heart-shapedcams, falls by a few degrees to turn the control shaft through the 180degree angle required by the usual type of con- 4 always applied fromthe same point on the positioning means, regardless of the direction ofrotation; but in the mechanism of the preceding figures, greaterleverage is provided through the use of separate arms and differentpoints of lever contact for each direction of rotation,

Fig. 6 illustrates a novel arrangement that makes it possible for thepositioning means to rotate the positionable member through an arc of180 degrees in either direction. This is achieved through the use of thelost-motion member 12, forming the contact projections D and E. Memberi2 is shaped so that projection D lies in a different plane than therest of the member. The lost-motion link I2 is pivoted on stud Q onlever L, and has'a projecting tappet I3, adapted to engage themotion-limiting abutments i4 and IS on lever L. As in the precedingfigures, 'arms B and C move in the same planes as projections D and Brespectively, and arms G and K are in the plane of positioning member F.When the positionable member approaches its extreme clockwise position,arm C engages projection E, and arm B engages projection D, thus movingthe lost-motion member to the position shown in full lines in thefigure. When button P is pressed down, projection E engages arm C androtates the positionable member counterclockwise until arm G is in aposition to be engaged by the positioning member F, which turns thepositionable member to the tuned-in position as in the precedingfigures.

If shaft S turns the positionable member counterclockwise, arms C and Bwill engage their cooperating contact projections and turn member Itwill now be seen that the downward movement of the operating lever willturn the positionable member in a clockwise direction until arm K isready to be engaged by positioning member F, which rotates member A tothe tuned-in position 180 degrees from the position shown in the figure.

In this modification, each positionable member of course has a setscrew,but this not shown plane.

in Fig. 6, as the set-screw provision involves no the desired rotationof degrees in either direction is accomplished by a lost-motion link, asin the embodiment of Fig. 6, but in this case the link is on therotatable member. The contact projections E and D, unlike those in anyof the previous figures, are both in the same Member l'l. of whichprojections E and D are apart, is offset at one end, as clearly shown inFig. 10, to permit attachment to member F by rivets l8 or other suitablemeans. Members F and II have holes W and V respectively at the end ofthe operatingmeans opposite to that carrying button P. These holes arefor shaft Q, as indicated in the other figures of this group.Positionable member A embraces arms G and K, shaped substantially as inthe foregoing figures, and is also provided, as in the othermodifications, with a set-screw .R in the hub, Fig. 11.

to the shaft on which the member is mounted.

This tappet is adapted to limit the rotation of lost-motion link 92 ineither direction with respect to member A. Link i2 is free to turn onshaft S excepting when in contact with tappet IS, in which cas link I!and member A turn as a unit. Tappet projection l5 should preferablyextend slightly beyond link l2, in order that the projection may abutagainst the next positionable member that may be assembled on shaft S,permitting link I! to turn freely without any unnecessary friction onthe sides.

In Fig. 'l, the positionable member A is shown in the extremecounterclockwise position. Link I2 is in engagement with projection Dand with tappet it on the positionable member. when the operating meansis pressed down, the pressure of contact projection D is transmitted bythe link to the tappet, and member A is therefore rotated until the linklies between the two contact projections. Th link is shown in thisposition in full lines in 'Fig. 8. As the positionable member ispictured here, arm K has already jection E, which presses on link l2;and the link, being in engagement with tappet l8, rotates the memberuntil arm G is in position to be turned by positioning member F. Thedotted-line view in Fig. 9 shows the link and positionable member stillturning as a unit under the pressure of projection E, just before arm 0has moved under positioning member F, which then turns the positionablemember to the tuned-in position as explained in connection withmodifications previously described. The link, however, is free fromengagement with the positionable member as soon as arm G receives thepressure 'of positioning element F, and it then hangs loosely on theshaft betweenthe projections.

In a complete tuner using this mechanism, a plurality of positionablemembers with accompanying links are assembled on shaft S as indicated inFig. 11. A plurality of operating means are pivoted on rod Q, andnormally held against bumper I! by individual springs J, all but one ofwhich are omitted from the figure to avoid obscuring other details.Bumper I is pictured as a tube on rod Q6 extending, lik rod Q, fromendplate XI to end-plate X2. These rods may be made to serve theadditional function of assisting bar 20 to support the frame. Shaft S,as in Fig. 1, is journaled in the end-plates. The tuner is mounted onchassis Y by means of screws 2|. the tuning device pictured in Fig. 11,th endplates also support tuning scale 22. If provisions are made forthe automatic tuning of only a few stations, the scale is apt to extendbeyond the operating means. If it is desired to arrange themsymmetrically with respect to the tuning scale, the operating means maybe centered between two collars 23 and 24, fastened on shaft Q by meansof screws 25 and 26 respectively. The positionable members are picturedsimilarly centered between collars 21 and 28, having setscrews 29 and 30respectively.

The horizontal tuning scale 22 has amovable pointer 3|, which must bemoved across the scale by the rotation of tuning shaft S. This isaccomplished by a simple novel drive that adds very little to the torquerequired to turn this shaft. In the usual drive to a tuning scale, onlyone pulley is used on the driving shaft, and the cord is made to doubleback so that both ends may be fastened to the driving pulley. Thisrequires that the cord pass around an extra idler pulley, and thedoubling back has a snubbing action that materially adds to the load.The driveshown in Figs. 11, 12 and 13, however, is extremely easy tooperate. Two pulleys 32 and 33 are keyed to shaft S on opposite sides ofthe assembly by screws or pins 34. A cord 35, fastened to pulley 32 atpoint 35, passes down around this pulley and then around idler pulley31, turning on stud 38 on bracket 39, which is integral with end-plateXI. Bracket 39 is formed at an angle that will permit cord 35 to remainin the same plane until it passes beyond pulley 31, as shown in Fig. 13.Cord 35 is fastened to the mounting 40 of pointer 3|. A spring 4| isfastened to the other side of the mounting, and to cord 42, which passesaround idler pulley 43 turning on stud 44 in bracket 45, formed onend-plate X2. As pictured in Fig. 12, pulley 43 lies in a verticalplane, permitting cord 42 to pass directly down and around pulley 33, towhich it is attached at point 46. 1

As shown in Fig. 11, the positionable members are mounted directly on along condenser shaft. Ordinarily, difllculty would arise in aligning thebearings for this shaft, inasmuch as the condenser usually has anindependent mounting; but in the arrangement shown in the figure, thisdifllculty is avoided by supporting the condenser on rubber, anexpedient often used to reduce mi.- crophonic effects. Such a rubbersupport, however, must have suflicient rigidity to keep'the condenser oneven keel.

Pulleys Zl and Z2 are for the manual drive, and function as do thecorresponding. pulleys in Fig. 1.

In the embodiment of the invention Just explained, the positionablmembers are set' in the same manner as those shown in Figs. 1 to 4.However, the arrangement of the set-screw R with relation to theoperating button P'ls improved, as the positioning member is offset at41, Fig. 10, so that the set-screw comes directly under thecorresponding button 13, as shown in Fig. 11.

Figs. 14, and 16 illustrate a modification in which the operating meansmoves in a straight line, rather than in an are as in the previouslydescri d embodiments. This modification is applicab to any of themechanisms shown in the preceding figures, but the configuration of thecooperating parts must be altered somewhat. The type of positionablemember pictured in the drawings is that shown in Figs. 7, 8 and 9, butinasmuch as the positioning element F moves directly down on thepositionable member, thus engaging either arm KB or KL at the sameangle, both of thesearms have the same contour. are identical to thosepreviously described. The curved contact surfaces D and E have the samefunction as the parts bearing the same reference letters in otherfigures, and the mechanism operates substantially the same as themechanisms of the-other embodiments. ,In this form of the device, thepositioning means must have guides to serve the purpose of rod Q in thepivoted type. These guides should be located as far apart as possible inorder to reduce play to a minimum and prevent binding. Guide bar Qextends all the way across the device from end-plate XI to end-plate X2,Fig. 16, and is apertured to form bearings or guides for the plungers P.Member 11, on which contacts E and D are formed, terminates in endpieces 48 and 49, passing through holes in guide member Q6. Each oftheseend bars '48 and 49 is surrounded by a spring, abutting against memberQ5 and pressing against shoulder 5|, thu forcing the operating meansupward until the top edges of members F and I1 rest against member Q.

If plunger P, Fig. 14, is pressed down on a positionable member andlost-motion link occupying the extreme clockwise position shown in fulllines, the curved contact'portion E will engage link J2, resting ontappet l6; and when the button on the plunger occupies the positionindicated in dotted lines, the positionable member wilLhave been movedto the dotted line position with positioning element 'F pressing on armKL, and the further downward movement of the operating means will rotatethe positionable member to the left until the operating means andpositionable member occupy the tuned-in position pictured in Fig. 15.

, The manner in which the operating means turns the positionable memberto the right, or in a clockwise direction, will be evident from thdescription of the preceding figures.

In the plunger, or push-button, -operated tuner illustrated in Fig. 16,a plurality of positionable members are mounted directly on the shaft Sof condenser 53, shown diagrammatically. Shaft S has a bearing at 54 inend-plate XI, but end-plate X2 has an aperture 55 much larger than theshaft, and, in some assemblies, even larger than the drawn-portion 56that houses the customary ball-race that forms one bearing for thecondenser shaft in the condenser end-plate 51, shown bolted to end-plateX2 of the tuner. Pulleys Zl and Z2 belong to the type of manual drivedescribed in connection with Fig. 1.

As shown in Fig. 14, it is possible to draw the escutcheon I, asindicated at 58, so that the operating button, in its downward stroke,may pass beneath the plane of the escutcheon, as shown in Fig. 15, thusreducing the amount that the plungers extend above the top of the set.Es-

cutcheon I is shown resting on one edge I! of The tappet and lost-motionlink shown" an opening 88 in the top panel of theset, and IThesecondcamthatwassetwillnow have moved the escutcheon has an aperture80 at the bottom 'to the left to a position 10 from its tuned-in, of-thedrawn section to permit, the plunger to positionwith the end KR.elevated above and to pass through. The escutcheon extends. of course,the-right of shaft 8. The link l2 associated with across theentireautomatic tuning device, and 5 this cam will remain in its hangingposition, as the long trough II has an aperture at the botthe mechanismdescribed and illustrated permits tom for each of the plungers. Theescutcheon about 80 degrees of movement of any member also carries anindex-tab holder M, extending KL-KR. from its tuned-in position beforelink along the edge of the drawn section, and havl2 starts to move. Itwill be obvious that the ing a window N substantially adjacent to eachPlunger for the second adjusted cam may now plunger through which thestation call-letters be depressed and the cam rotated to the clockwisemay be read on the index tab 0 in the recess position for which it wasset without the link l2 between holder M and the escutcheon proper.associated with either of the adjusted cams com- The push-button tuneris set in the following in: into play. Now suppose a third positionablemanner: Tab v0 is removed from under the winmember KL-KR. is set for anangular position dow N by the plunger that is to tune-in the demidwaybetween the two extremes of rotation. sired station, and the plunger isthen pushed all When this third cam is in its tuned-in position, the waydown to the position pictured in Fig. 15. end KL of the first adjustedcam will be raised This causes set-screw R to come into alignment 35 andend KB of the second cam will be raised with hole U in the escutcheon atthe bottom of 35. If these three cams are set for the angular theindex-tab compartment. A screw-driver is positions indicated d shaft 5is turned to its then inserted through window N and hole U, andcounter-clockwise ext eme, the first cam will be the set-screw loosened.While still holding the in the tuned-in position illustrated in Fig. 15;plunger down, the desired station is tuned-in end KR of the third camwill be raised 35; and by the regular manual tuning knob as carefullyend KR of the second adjusted cam will be as possible. The set-screw isthen tightened raised 70. If shaft 8 is now turned to the clock again,and the proper index-tab placed in the wise extreme of its, required 70angle of rotation, holder, the second adjustedcam will be in theposition Suppose that the satisfactory operation of the shown in Fig.15; the third adjusted cam will condenser to which the device isattached, rehave its KL end raised and end KL of the quires shaft S toturn through a maximum arc of first adjusted cam will be elevated 70.The 70". Additional rotation of this shaft, let us say, plungers forthese three cams may now be is not necessary either because thecondenser is pressed at random to rotate shaft S to any of of a type inwhich the rotor blades. can be moved the three positions for which thepositionable completely in and out of mesh by a movement 35 members.have been set. and although two of through a 70 angle, or because themotion is these positions 'are the extremes of the 70 angle stepped upto 180 by gears, pulleys and a belt, of rotation, the links l2 and theassociated shoul o motion-multiplying linkage h as that ders E and Dnever come into engagement. Inshown in Fig. 2 of the Carlson Patent No.mlich as part l2 and shoulders E and D thus 1,964,449. Suppose one ofthe positionable mem- 40 all not co e P Within the range of angubersKlr-KR. is being set so that the operation 1&1 movement just described,it is obvious that of t plunger p 111 move t shaft, t th u they are notrequired in the device when its tor-clockwise extreme of its angle ofrotation. n e is to be within these limits. With set screw R loosenedand the plunger held. Fig. i! is introduced to illustrate how rollersdown, the manual knob (not shown) which opery be m t t P s Of contact inny of t pulley 32, Fig 1 is turned m shaft 5 the embodiments describedin this specification has been rotated as far as possible to the left.and ill-filmed the awin s- 'The embodiment Allduring this settingoperation, the plunger, shown is the one just described. Rollers E andand cam KL-m will be in the position shown B are pivoted on studs i meme and obin Fig. 15, but shaft S will turn within the cam. Viously ve thes Purpose s the rounded After the shaft has been rotated. to its endposicomers E n D in Fi s. 14 and 15. These rollti i t manner justdescribed, t screw R 1 ers reduce friction somewhat, but inasmuch astighgene Now Suppose another positionable they involve an additionalcost for each lever member or cam KL-KR is to be set for the and thusincrease t 's i s price o t set. I clockwise extreme of the 70 angle ofrotation P f r instead to use suitable contours on t required of shaftWhfle t set anew of rounded contact edges andtoconstruct the memthissecond cam remains released with t 8530. bers from metals that slidewith a minimum of dated plunger m down, haft 3 is rotated t friction.Rollers GI and 6.! reduce the rotational t other extreme of the required70 angle of resistance of the positionable member when enrotation, andthe set screw is then tightened to di s by memberFof n ra ine means.This lock the cam inits adjusted position on the shaft. p ient may beused on any f the various The second cam will now be in the positionshown forms i the invention, h h Proper contours in Fig. 15, and thecamthat was set for the counand Proper metals ly make rollersunnecester-clockwise extreme of rotationwill have moved ms G n in thedifferent figures, during thi operation t th position Shown in operatevery satisfactorily if their contours are broken lines in Fig. 14, butlink I: will remain substantially s shown.

unengaged and undisturbed in the position shown The condenser Shaft, n yof the modifica- I in broken lines in Fig. 14, which is the samepotions. may be co e d to shaft 8 by a oup in sition as that showninfull lines in Fig. 15. Supas in i te in Fi s ft 5 y be the pose t t itis now d i t utmz th tuning shaft of the condenser itself; and variousways mechanism to rotate shafts to the counterof mountingthe condenserand eliminating extra clockwise extreme automatically. The plungerbearings, of which those shown in Figs. 11 and for the cam that was setfor this position will 16 are typical, may be used interchangeably inengage the cam as shown in broken lines in Fig. any of the embodiments.14 and move it to the position shown in Fig. 15. Still othermodifications will be evident to typical embodiments.

My claims are:

1. In a mechanism for positioning a control, a combination including: amovable operating means; and a rotatable positionable member comprisingfour arms each adapted to be engaged by diiferent portions of said meansfor turning said member each in one direction through a substantiallydifferent sector.

2. In a mechanism for angularly positioning a control, a combinationincluding: a movable operating means; and a rotatable positionablemember comprising three arms each adapted to be engaged by saidoperating means and each lying in a different plane.

3. In a mechanism for positioning a control, a combination including: amovable operating member; a rotatable positionable member adapted to beturned to an angular position that is common to either extremeof itsrotary motion; and an element for transmitting motion 'from saidoperating member to said positionable member and having a lost-motionconnection with at least one of said members, said element adapted toassume different positions when said positionable member is in saidangular position, the position of said element depending upon whichextreme of its motion has been reached by said positionable member.

4. In a mechanism for positioning a control,

a combination including: a rotatable positionsition at which boththesecond and third arms are simultaneously in engagement with said lattermeans.

5. In a mechanism for positioning a control, a combination including: arotatable element; a plurality of rotatable positionable means; and aplurality of independently movable operatin means each individual to oneof said positionable means; each of said positionable means comprisingboth a member adiustably mounted on said element and a lost-motion linkfree to turn around said element, said link adapted to transmit motionfrom the corresponding operating means to the associated member, andsaid member having means for preventing side friction from interferingwith the free rotation of said link, said latter means comprising aproiection extending from said member in a direction parallel to saidelement and passing at least slightly beyond said link. v

6. In a radio control mechanism, a combination including: a rotatablepositionable member; positioning'means for turning said positionablemember in either direction, said means comprising a longitudinallymovable operating element having legs adapted to straddle said member; asupporting guide for each of said legs; and at least one supp rtingguide for said element located on the opposite side of the axis ofrotation of said member from said first-mentioned guides.

7. In a radio control mechanism, a combination including: a rotatableshaft; a positionable member adjustably mounted on said shaft;positioning instrumentalities for turning said member in eitherdirection; said instrumentalities comprising a longitudinally movabledevice having legs adapted to straddle said shaft; saidinstrumentalities also comprising an element operatively interposedbetween said device and said member and adapted through a lost-motionconnection to transmit motion from said device to said member; and asupporting guide for at least one of saidlegs.

8. In a radio control mechanism, a combination including: a rotatableshaft; a plurality of positionable members adjustably mounted on saidshaft; a plurality of positioning instrumentalities for turning saidmembers and shaft in either direction; each of said' instrumentalitiescomprising a longitudinally movable device having a plurality ofsupporting guides; each of said instrumentalities also comprising anelement free to turn around said shaft and adapted through a lost-motionconnection to transmit motion from the associated device to one of saidmembers; and means for preventing side friction from interfering withthe free angular movement of said elements.

9. In a radio control mechanism, a combination including: a rotatableshaft; a plurality of positionable members adjustably mounted on saidshaft; a plurality of movable operating devices for positioning saidmembers, said devices each having legs adapted to straddle said shaft;a. plurality of elements each having a lost-mooperative positions.

10. In a mechanism for positioning a control, a combination including: amovable operating means; a rotatable positionable means; and a memberfor transmitting motion from said operating means to said positionablemeans for turning said positionable means from certain angularpositions, said member having a lostmotion connection with at least oneof said means; said positionable means adapted to be rotated fromcertain other angular positions by the direct engagement and movement ofsaid operating means.

11. In a mechanism for positi ning a control of a radio device, acombination ncluding: a rotatable shaft; a positionable structureadjustably mounted upon said shaft; positioning means for turning saidstructure in either direction to a position at which said means pressesagainst said structure on opposite sides of its rotational axis insubstantially parallel directions; said means having a first shoulderadapted t engage and turn said structure in one direction only and asecond shoulder adapted to engage and turn said structure in the.opposite direction only, said means having a recess between saidshoulders to permit said shoulders to pass over said shaft.

12. In ameohanism for positioning a control, a combination including: arotatable positionable structure comprising first; second and third anda second shoulder adapted to engage said first arm and turn saidstructure-in an opposite direction; said membefalso having ,means forengaging said second and third arms and rotating at least a part of saidstructure in one direction when the second arm is engaged and in theopposite direction when the third arm is engaged; said member having arecess between said shoulders to receive said first arm when said memberis in engagement with either of the other arms.

13. In a radio control device, a combination including: a rotatablestructure; and a rectilin-' early movable operating device for rotatingsaid structure; said device comprising at least one supporting armdisposed to move in a path at one side of said structure, and a pair ofshoulders adapted to engage said structure on opposite sides of the axisof said structure and rotate said structure in respectively oppositedirections, one of said shoulders positioned substantially between theother shoulder and said arm.

=structure in either direction to a position at which said devicepresses against said structure on both sides of said shaft insubstantially parallel directions, said device comprising at least onesupporting arm disposed to move in a path lying on one side of saidshaft and transverse thereto, and a pair of shoulders adapted to engagesaid structure on opposite sides of said shaft and rotate saidstructure'in respectively opposite directions only; said device having arecess between said shoulders to permit said shoulders to pass over'saidshaft.

15. In a radio control mechanism, a combination including: a rotatablepositionable member; positioning means for turning. said positionablemember in either direction, said means comprising a. longitudinallymovable operatingelement having legs adapted to straddle said member;supporting and guiding means for said legs; and at least one supportingguide for said element.

-16. In a radio control mechanism, a combinainstrumentalities forturning said shaft in either direction; said instrumentalitiescomprising a longitudinally movable element having legs adapted tostraddle said shaft; supporting and guiding means for said legs; and atleast one supporting guide for said element; said instrumentalities alsocomprising .an adjustable member operatively interposed betweensaid/element and said shaft for predetermining the angular position towhich said shaft will be rotated upon movement of said element in onedirection.

17. In a mechanism for positioning a control of a radio device, acombination including: a rotatable positionable member; a movableactuating means comprising a motion-initiating member and an elementadapted to have a' lostmotion operating connection with bothsaidactuating means and said positionable member whereby motion may betransmitted from said actuating means to said positionable member uponmovement of said motion-initiating member in one'direction.

18. A mechanical station selector type tuner' for a radio receivercomprising, in combination,

an actuator movable generally rectilinearly and having a recess in itsforward end bordered by spaced forwardly projecting portions on oppositesides thereof, a rotatable positionable structure positioned in front ofsaid actuator and comprising an elongated generally fiat peripheral camlying in the plane of said projecting portions of said actuator andoscillatable in said plane about an axis longitudinally eceentric'to thecenter of said elongated cam and transverse to the path of movement ofsaid actuator, means for connecting said structure in driving relationwith the tuning element of a radio receiver, and means for moving saidactuator toward said structure to cause said projecting portions of saidactuator to contact and push alternative adjacent edges of said cam andto cause said actuator to apply a moving force to said structure androtate it to a position in which the longitudinal axis of said elongatedcam projects away from said actuator insubstantial ably mounted upon,said shaft and comprising a plurality of peripheral cam face portionseach extending in a direction away from said shaft;

positioning means for turning said structure in either direction to aposition I in which saidmeans presses on said structure on oppositesides of its rotational axis simultaneously and in substantiallyparallel directions; said positioning means adaptedto rotate saidstructure in I opposite directions solely by the application of -tionincluding: a rotatable shaft; positioning ing, in combination: anactuator movable generally rectilinearly and having a recess in itsfortion in said plane about an axis longitudinally pressure to said camportions from totally diiferent portions of said means, and having afirst shoulder adapted to engage and turn said structure in onedirection only and a second -shoulder adapted to engage and turn saidstructure in the opposite direction only, said means havward endbordered by spaced forwardLv projecting'portions on opposite sidesthereof, an elongated generally flat peripheral cam positioned in frontof said actuator and lying in the plane of said projecting portions ofsaid actuator, ineans for supporting said cam for oscillaeccentric tothe center of said elongated cam and transverse to the path of movementof said actuator. andwith the outermost end of said cam facing generallyaway from said actuator and never directly toward the'same, means forconnecting said cam in driving relation with said control shaft, andmeans for moving said actu'ator toward said cam to cause said .projectfrom said' actuator in substantial alinement therewith.

- LE BOY J. LEISHMAN.

